If a client sends a READDIR count argument that is too small (say,
zero), then the buffer size calculation in the new init_dirlist
helper functions results in an underflow, allowing the XDR stream
functions to write beyond the actual buffer.

This calculation has always been suspect. NFSD has never sanity-
checked the READDIR count argument, but the old entry encoders
managed the problem correctly.

With the commits below, entry encoding changed, exposing the
underflow to the pointer arithmetic in xdr_reserve_space().

Modern NFS clients attempt to retrieve as much data as possible
for each READDIR request. Also, we have no unit tests that
exercise the behavior of READDIR at the lower bound of @count
values. Thus this case was missed during testing.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Fixes: f5dcccd647da ("NFSD: Update the NFSv2 READDIR entry encoder to use struct xdr_stream")
Fixes: 7f87fc2d34d4 ("NFSD: Update NFSv3 READDIR entry encoders to use struct xdr_stream")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

A delegation break could arrive as soon as we've called vfs_setlease.  A
delegation break runs a callback which immediately (in
nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru.  If we
then exit nfs4_set_delegation without hashing the delegation, it will be
freed as soon as the callback is done with it, without ever being
removed from del_recall_lru.

Symptoms show up later as use-after-free or list corruption warnings,
usually in the laundromat thread.

I suspect aba2072f4523 "nfsd: grant read delegations to clients holding
writes" made this bug easier to hit, but I looked as far back as v3.0
and it looks to me it already had the same problem.  So I'm not sure
where the bug was introduced; it may have been there from the beginning.

Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Commit bd5ae9288d64 ("nfsd: register pernet ops last, unregister first")
has re-opened rpc_pipefs_event() race against nfsd_net_id registration
(register_pernet_subsys()) which has been fixed by commit bb7ffbf29e76
("nfsd: fix nsfd startup race triggering BUG_ON").

Restore the order of register_pernet_subsys() vs register_cld_notifier().
Add WARN_ON() to prevent a future regression.

Crash info:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000012
CPU: 8 PID: 345 Comm: mount Not tainted 5.4.144-... #1
pc : rpc_pipefs_event+0x54/0x120 [nfsd]
lr : rpc_pipefs_event+0x48/0x120 [nfsd]
Call trace:
 rpc_pipefs_event+0x54/0x120 [nfsd]
 blocking_notifier_call_chain
 rpc_fill_super
 get_tree_keyed
 rpc_fs_get_tree
 vfs_get_tree
 do_mount
 ksys_mount
 __arm64_sys_mount
 el0_svc_handler
 el0_svc

Fixes: bd5ae9288d64 ("nfsd: register pernet ops last, unregister first")
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Pull nfsd bugfix from Bruce Fields:
 "This is just one bugfix for a buffer overflow in knfsd's xdr decoding"

* tag 'nfsd-5.16-1' of git://linux-nfs.org/~bfields/linux:
  NFSD: Fix exposure in nfsd4_decode_bitmap()

rtm@csail.mit.edu reports:
> nfsd4_decode_bitmap4() will write beyond bmval[bmlen-1] if the RPC
> directs it to do so. This can cause nfsd4_decode_state_protect4_a()
> to write client-supplied data beyond the end of
> nfsd4_exchange_id.spo_must_allow[] when called by
> nfsd4_decode_exchange_id().

Rewrite the loops so nfsd4_decode_bitmap() cannot iterate beyond
@bmlen.

Reported by: rtm@csail.mit.edu
Fixes: d1c263a031e8 ("NFSD: Replace READ* macros in nfsd4_decode_fattr()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Pull nfsd updates from Bruce Fields:
 "A slow cycle for nfsd: mainly cleanup, including Neil's patch dropping
  support for a filehandle format deprecated 20 years ago, and further
  xdr-related cleanup from Chuck"

* tag 'nfsd-5.16' of git://linux-nfs.org/~bfields/linux: (26 commits)
  nfsd4: remove obselete comment
  nfsd: document server-to-server-copy parameters
  NFSD:fix boolreturn.cocci warning
  nfsd: update create verifier comment
  SUNRPC: Change return value type of .pc_encode
  SUNRPC: Replace the "__be32 *p" parameter to .pc_encode
  NFSD: Save location of NFSv4 COMPOUND status
  SUNRPC: Change return value type of .pc_decode
  SUNRPC: Replace the "__be32 *p" parameter to .pc_decode
  SUNRPC: De-duplicate .pc_release() call sites
  SUNRPC: Simplify the SVC dispatch code path
  SUNRPC: Capture value of xdr_buf::page_base
  SUNRPC: Add trace event when alloc_pages_bulk() makes no progress
  svcrdma: Split svcrmda_wc_{read,write} tracepoints
  svcrdma: Split the svcrdma_wc_send() tracepoint
  svcrdma: Split the svcrdma_wc_receive() tracepoint
  NFSD: Have legacy NFSD WRITE decoders use xdr_stream_subsegment()
  SUNRPC: xdr_stream_subsegment() must handle non-zero page_bases
  NFSD: Initialize pointer ni with NULL and not plain integer 0
  NFSD: simplify struct nfsfh
  ...

Pull NFS client updates from Trond Myklebust:
 "Highlights include:

  Features:
   - NFSv4.1 can always retrieve and cache the ACCESS mode on OPEN
   - Optimisations for READDIR and the 'ls -l' style workload
   - Further replacements of dprintk() with tracepoints and other
     tracing improvements
   - Ensure we re-probe NFSv4 server capabilities when the user does a
     "mount -o remount"

  Bugfixes:
   - Fix an Oops in pnfs_mark_request_commit()
   - Fix up deadlocks in the commit code
   - Fix regressions in NFSv2/v3 attribute revalidation due to the
     change_attr_type optimisations
   - Fix some dentry verifier races
   - Fix some missing dentry verifier settings
   - Fix a performance regression in nfs_set_open_stateid_locked()
   - SUNRPC was sending multiple SYN calls when re-establishing a TCP
     connection.
   - Fix multiple NFSv4 issues due to missing sanity checking of server
     return values
   - Fix a potential Oops when FREE_STATEID races with an unmount

  Cleanups:
   - Clean up the labelled NFS code
   - Remove unused header <linux/pnfs_osd_xdr.h>"

* tag 'nfs-for-5.16-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (84 commits)
  NFSv4: Sanity check the parameters in nfs41_update_target_slotid()
  NFS: Remove the nfs4_label argument from decode_getattr_*() functions
  NFS: Remove the nfs4_label argument from nfs_setsecurity
  NFS: Remove the nfs4_label argument from nfs_fhget()
  NFS: Remove the nfs4_label argument from nfs_add_or_obtain()
  NFS: Remove the nfs4_label argument from nfs_instantiate()
  NFS: Remove the nfs4_label from the nfs_setattrres
  NFS: Remove the nfs4_label from the nfs4_getattr_res
  NFS: Remove the f_label from the nfs4_opendata and nfs_openres
  NFS: Remove the nfs4_label from the nfs4_lookupp_res struct
  NFS: Remove the label from the nfs4_lookup_res struct
  NFS: Remove the nfs4_label from the nfs4_link_res struct
  NFS: Remove the nfs4_label from the nfs4_create_res struct
  NFS: Remove the nfs4_label from the nfs_entry struct
  NFS: Create a new nfs_alloc_fattr_with_label() function
  NFS: Always initialise fattr->label in nfs_fattr_alloc()
  NFSv4.2: alloc_file_pseudo() takes an open flag, not an f_mode
  NFS: Don't allocate nfs_fattr on the stack in __nfs42_ssc_open()
  NFSv4: Remove unnecessary 'minor version' check
  NFSv4: Fix potential Oops in decode_op_map()
  ...

Pull fsnotify updates from Jan Kara:
 "Support for reporting filesystem errors through fanotify so that
  system health monitoring daemons can watch for these and act instead
  of scraping system logs"

* tag 'fsnotify_for_v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: (34 commits)
  samples: remove duplicate include in fs-monitor.c
  samples: Fix warning in fsnotify sample
  docs: Fix formatting of literal sections in fanotify docs
  samples: Make fs-monitor depend on libc and headers
  docs: Document the FAN_FS_ERROR event
  samples: Add fs error monitoring example
  ext4: Send notifications on error
  fanotify: Allow users to request FAN_FS_ERROR events
  fanotify: Emit generic error info for error event
  fanotify: Report fid info for file related file system errors
  fanotify: WARN_ON against too large file handles
  fanotify: Add helpers to decide whether to report FID/DFID
  fanotify: Wrap object_fh inline space in a creator macro
  fanotify: Support merging of error events
  fanotify: Support enqueueing of error events
  fanotify: Pre-allocate pool of error events
  fanotify: Reserve UAPI bits for FAN_FS_ERROR
  fsnotify: Support FS_ERROR event type
  fanotify: Require fid_mode for any non-fd event
  fanotify: Encode empty file handle when no inode is provided
  ...

Refactor: surface useful show_ macros so they can be shared between
the client and server trace code.

Additional clean up:
- Housekeeping: ensure the correct #include files are pulled in
  and add proper TRACE_DEFINE_ENUM where they are missing
- Use a consistent naming scheme for the helpers
- Store values to be displayed symbolically as unsigned long, as
  that is the type that the __print_yada() functions take

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Mandatory locking has been removed.  And the rest of this comment is
redundant with the code.

Reported-by: Jeff layton <jlayton@kernel.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>